Quarkus Tdd

Quarkus TDD Workflow

TDD guidance for Quarkus 3.x services with 80%+ coverage (unit + integration). Optimized for event-driven architectures with Apache Camel.

When to Use

• New features or REST endpoints
• Bug fixes or refactors
• Adding data access logic, security rules, or reactive streams
• Testing Apache Camel routes and event handlers
• Testing event-driven services with RabbitMQ
• Testing conditional flow logic
• Validating CompletableFuture async operations
• Testing LogContext propagation

Workflow

1. Write tests first (they should fail)
2. Implement minimal code to pass
3. Refactor with tests green
4. Enforce coverage with JaCoCo (80%+ target)

Unit Tests with @Nested Organization

Follow this structured approach for comprehensive, readable tests:

@ExtendWith(MockitoExtension.class)
@DisplayName("OrderService Unit Tests")
class OrderServiceTest {

  @Mock
  private OrderRepository orderRepository;

  @Mock
  private EventService eventService;

  @Mock
  private FulfillmentPublisher fulfillmentPublisher;

  @InjectMocks
  private OrderService orderService;

  private CreateOrderCommand validCommand;

  @BeforeEach
  void setUp() {
    validCommand = new CreateOrderCommand(
        "customer-123",
        List.of(new OrderLine("sku-123", 2))
    );
  }

  @Nested
  @DisplayName("Tests for createOrder")
  class CreateOrder {

    @Test
    @DisplayName("Should persist order and publish fulfillment event")
    void givenValidCommand_whenCreateOrder_thenPersistsAndPublishes() {
      // ARRANGE
      doNothing().when(orderRepository).persist(any(Order.class));

      // ACT
      OrderReceipt receipt = orderService.createOrder(validCommand);

      // ASSERT
      assertThat(receipt).isNotNull();
      assertThat(receipt.customerId()).isEqualTo("customer-123");
      verify(orderRepository).persist(any(Order.class));
      verify(fulfillmentPublisher).publishAsync(receipt);
      verify(eventService).createSuccessEvent(receipt, "ORDER_CREATED");
    }

    @Test
    @DisplayName("Should reject missing customer id")
    void givenMissingCustomerId_whenCreateOrder_thenThrowsBadRequest() {
      // ARRANGE
      CreateOrderCommand invalid = new CreateOrderCommand("", validCommand.lines());

      // ACT & ASSERT
      WebApplicationException exception = assertThrows(
          WebApplicationException.class,
          () -> orderService.createOrder(invalid)
      );

      assertThat(exception.getResponse().getStatus()).isEqualTo(400);
      verify(orderRepository, never()).persist(any(Order.class));
      verify(fulfillmentPublisher, never()).publishAsync(any());
    }

    @Test
    @DisplayName("Should record error event when persistence fails")
    void givenPersistenceFailure_whenCreateOrder_thenRecordsErrorEvent() {
      // ARRANGE
      doThrow(new PersistenceException("database unavailable"))
          .when(orderRepository).persist(any(Order.class));

      // ACT & ASSERT
      PersistenceException exception = assertThrows(
          PersistenceException.class,
          () -> orderService.createOrder(validCommand)
      );

      assertThat(exception.getMessage()).contains("database unavailable");
      verify(eventService).createErrorEvent(
          eq(validCommand),
          eq("ORDER_CREATE_FAILED"),
          contains("database unavailable")
      );
      verify(fulfillmentPublisher, never()).publishAsync(any());
    }

    @Test
    @DisplayName("Should reject null commands")
    void givenNullCommand_whenCreateOrder_thenThrowsNullPointerException() {
      // ACT & ASSERT
      assertThrows(
          NullPointerException.class,
          () -> orderService.createOrder(null)
      );

      verify(orderRepository, never()).persist(any(Order.class));
    }
  }
}

Key Testing Patterns

1. @Nested Classes: Group tests by method being tested
2. @DisplayName: Provide readable test descriptions for test reports
3. Naming Convention: givenX_whenY_thenZ for clarity
4. AAA Pattern: Explicit // ARRANGE, // ACT, // ASSERT comments
5. @BeforeEach: Setup common test data to reduce duplication
6. assertDoesNotThrow: Test success scenarios without catching exceptions
7. assertThrows: Test exception scenarios with message validation using AssertJ
8. Comprehensive Coverage: Test happy paths, null inputs, edge cases, exceptions
9. Verify Interactions: Use Mockito verify() to ensure methods are called correctly
10. Never Verify: Use never() to ensure methods are NOT called in error scenarios

Testing Camel Routes

@QuarkusTest
@DisplayName("Business Rules Camel Route Tests")
class BusinessRulesRouteTest {

  @Inject
  CamelContext camelContext;

  @Inject
  ProducerTemplate producerTemplate;

  @InjectMock
  EventService eventService;

  @InjectMock
  DocumentValidator documentValidator;

  private BusinessRulesPayload testPayload;

  @BeforeEach
  void setUp() {
    // ARRANGE - Test data
    testPayload = new BusinessRulesPayload();
    testPayload.setDocumentId(1L);
    testPayload.setFlowProfile(FlowProfile.BASIC);
  }

  @Nested
  @DisplayName("Tests for business-rules-publisher route")
  class BusinessRulesPublisher {

    @Test
    @DisplayName("Should successfully publish message to RabbitMQ")
    void givenValidPayload_whenPublish_thenMessageSentToQueue() throws Exception {
      // ARRANGE
      MockEndpoint mockRabbitMQ = camelContext.getEndpoint("mock:rabbitmq", MockEndpoint.class);
      mockRabbitMQ.expectedMessageCount(1);

      // Replace real endpoint with mock for testing
      camelContext.getRouteController().stopRoute("business-rules-publisher");
      AdviceWith.adviceWith(camelContext, "business-rules-publisher", advice -> {
        advice.replaceFromWith("direct:business-rules-publisher");
        advice.weaveByToString(".*spring-rabbitmq.*").replace().to("mock:rabbitmq");
      });
      camelContext.getRouteController().startRoute("business-rules-publisher");

      // ACT
      producerTemplate.sendBody("direct:business-rules-publisher", testPayload);

      // ASSERT — body is a JSON String after .marshal().json(JsonLibrary.Jackson)
      mockRabbitMQ.assertIsSatisfied(5000);

      assertThat(mockRabbitMQ.getExchanges()).hasSize(1);
      String body = mockRabbitMQ.getExchanges().get(0).getIn().getBody(String.class);
      assertThat(body).contains("\"documentId\":1");
    }

    @Test
    @DisplayName("Should handle marshalling to JSON")
    void givenPayload_whenPublish_thenMarshalledToJson() throws Exception {
      // ARRANGE
      MockEndpoint mockMarshal = new MockEndpoint("mock:marshal");
      camelContext.addEndpoint("mock:marshal", mockMarshal);
      mockMarshal.expectedMessageCount(1);

      camelContext.getRouteController().stopRoute("business-rules-publisher");
      AdviceWith.adviceWith(camelContext, "business-rules-publisher", advice -> {
        advice.weaveAddLast().to("mock:marshal");
      });
      camelContext.getRouteController().startRoute("business-rules-publisher");

      // ACT
      producerTemplate.sendBody("direct:business-rules-publisher", testPayload);

      // ASSERT
      mockMarshal.assertIsSatisfied(5000);

      String body = mockMarshal.getExchanges().get(0).getIn().getBody(String.class);
      assertThat(body).contains("\"documentId\":1");
      assertThat(body).contains("\"flowProfile\":\"BASIC\"");
    }
  }

  @Nested
  @DisplayName("Tests for document-processing route")
  class DocumentProcessing {

    @Test
    @DisplayName("Should route invoice to correct processor")
    void givenInvoiceType_whenProcess_thenRoutesToInvoiceProcessor() throws Exception {
      // ARRANGE
      MockEndpoint mockInvoice = camelContext.getEndpoint("mock:invoice", MockEndpoint.class);
      mockInvoice.expectedMessageCount(1);

      camelContext.getRouteController().stopRoute("document-processing");
      AdviceWith.adviceWith(camelContext, "document-processing", advice -> {
        advice.weaveByToString(".*direct:process-invoice.*").replace().to("mock:invoice");
      });
      camelContext.getRouteController().startRoute("document-processing");

      // ACT
      producerTemplate.sendBodyAndHeader("direct:process-document",
          testPayload, "documentType", "INVOICE");

      // ASSERT
      mockInvoice.assertIsSatisfied(5000);
    }

    @Test
    @DisplayName("Should handle validation errors gracefully")
    void givenValidationError_whenProcess_thenRoutesToErrorHandler() throws Exception {
      // ARRANGE
      MockEndpoint mockError = camelContext.getEndpoint("mock:error", MockEndpoint.class);
      mockError.expectedMessageCount(1);

      camelContext.getRouteController().stopRoute("document-processing");
      AdviceWith.adviceWith(camelContext, "document-processing", advice -> {
        advice.weaveByToString(".*direct:validation-error-handler.*")
            .replace().to("mock:error");
      });
      camelContext.getRouteController().startRoute("document-processing");

      // Mock validator bean to throw exception
      when(documentValidator.validate(any())).thenThrow(new ValidationException("Invalid document"));

      // ACT
      producerTemplate.sendBody("direct:process-document", testPayload);

      // ASSERT
      mockError.assertIsSatisfied(5000);

      Exception exception = mockError.getExchanges().get(0).getException();
      assertThat(exception).isInstanceOf(ValidationException.class);
      assertThat(exception.getMessage()).contains("Invalid document");
    }
  }
}

Testing Event Services

@ExtendWith(MockitoExtension.class)
@DisplayName("EventService Unit Tests")
class EventServiceTest {

  @Mock
  private EventRepository eventRepository;

  @Mock
  private ObjectMapper objectMapper;

  @InjectMocks
  private EventService eventService;

  private BusinessRulesPayload testPayload;

  @BeforeEach
  void setUp() {
    // ARRANGE
    testPayload = new BusinessRulesPayload();
    testPayload.setDocumentId(1L);
  }

  @Nested
  @DisplayName("Tests for createSuccessEvent")
  class CreateSuccessEvent {

    @Test
    @DisplayName("Should create success event with correct attributes")
    void givenValidPayload_whenCreateSuccessEvent_thenEventPersisted() throws Exception {
      // ARRANGE
      when(objectMapper.writeValueAsString(testPayload)).thenReturn("{\"documentId\":1}");

      // ACT
      assertDoesNotThrow(() ->
          eventService.createSuccessEvent(testPayload, "DOCUMENT_PROCESSED"));

      // ASSERT
      verify(eventRepository).persist(argThat(event ->
          event.getType().equals("DOCUMENT_PROCESSED") &&
          event.getStatus() == EventStatus.SUCCESS &&
          event.getPayload().equals("{\"documentId\":1}") &&
          event.getTimestamp() != null
      ));
    }

    @Test
    @DisplayName("Should throw exception when payload is null")
    void givenNullPayload_whenCreateSuccessEvent_thenThrowsException() {
      // ARRANGE
      Object nullPayload = null;

      // ACT & ASSERT
      NullPointerException exception = assertThrows(
          NullPointerException.class,
          () -> eventService.createSuccessEvent(nullPayload, "EVENT_TYPE")
      );

      assertThat(exception.getMessage()).isEqualTo("Payload cannot be null");
      verify(eventRepository, never()).persist(any());
    }
  }

  @Nested
  @DisplayName("Tests for createErrorEvent")
  class CreateErrorEvent {

    @Test
    @DisplayName("Should create error event with error message")
    void givenError_whenCreateErrorEvent_thenEventPersistedWithMessage() throws Exception {
      // ARRANGE
      String errorMessage = "Processing failed";
      when(objectMapper.writeValueAsString(testPayload)).thenReturn("{\"documentId\":1}");

      // ACT
      assertDoesNotThrow(() ->
          eventService.createErrorEvent(testPayload, "PROCESSING_ERROR", errorMessage));

      // ASSERT
      verify(eventRepository).persist(argThat(event ->
          event.getType().equals("PROCESSING_ERROR") &&
          event.getStatus() == EventStatus.ERROR &&
          event.getErrorMessage().equals(errorMessage) &&
          event.getPayload().equals("{\"documentId\":1}")
      ));
    }

    @ParameterizedTest
    @DisplayName("Should reject invalid error messages")
    @ValueSource(strings = {"", " "})
    void givenBlankErrorMessage_whenCreateErrorEvent_thenThrowsException(String blankMessage) {
      // ACT & ASSERT
      IllegalArgumentException exception = assertThrows(
          IllegalArgumentException.class,
          () -> eventService.createErrorEvent(testPayload, "ERROR", blankMessage)
      );

      assertThat(exception.getMessage()).contains("Error message cannot be blank");
    }
  }
}

Testing CompletableFuture

@ExtendWith(MockitoExtension.class)
@DisplayName("FileStorageService Unit Tests")
class FileStorageServiceTest {

  @Mock
  private S3Client s3Client;

  @Mock
  private ExecutorService executorService;

  @InjectMocks
  private FileStorageService fileStorageService;

  private InputStream testInputStream;
  private LogContext testLogContext;

  @BeforeEach
  void setUp() {
    // ARRANGE
    testInputStream = new ByteArrayInputStream("test content".getBytes());
    testLogContext = new LogContext();
    testLogContext.put("traceId", "trace-123");
  }

  @Nested
  @DisplayName("Tests for uploadOriginalFile")
  class UploadOriginalFile {

    @Test
    @DisplayName("Should successfully upload file and return document info")
    void givenValidFile_whenUpload_thenReturnsDocumentInfo() throws Exception {
      // ARRANGE
      doAnswer(invocation -> {
        ((Runnable) invocation.getArgument(0)).run();
        return null;
      }).when(executorService).execute(any(Runnable.class));

      when(s3Client.putObject(any(PutObjectRequest.class), any(RequestBody.class)))
          .thenReturn(PutObjectResponse.builder().build());

      // ACT
      CompletableFuture future =
          fileStorageService.uploadOriginalFile(testInputStream, 1024L,
              testLogContext, InvoiceFormat.UBL);

      StoredDocumentInfo result = future.join();

      // ASSERT
      assertThat(result).isNotNull();
      assertThat(result.getPath()).isNotBlank();
      assertThat(result.getSize()).isEqualTo(1024L);
      assertThat(result.getUploadedAt()).isNotNull();

      verify(s3Client).putObject(any(PutObjectRequest.class), any(RequestBody.class));
    }

    @Test
    @DisplayName("Should handle S3 upload failure")
    void givenS3Failure_whenUpload_thenCompletableFutureFails() {
      // ARRANGE — run synchronously so exception propagates through the future
      doAnswer(invocation -> {
        ((Runnable) invocation.getArgument(0)).run();
        return null;
      }).when(executorService).execute(any(Runnable.class));

      when(s3Client.putObject(any(PutObjectRequest.class), any(RequestBody.class)))
          .thenThrow(new StorageException("S3 unavailable"));

      // ACT
      CompletableFuture future =
          fileStorageService.uploadOriginalFile(testInputStream, 1024L,
              testLogContext, InvoiceFormat.UBL);

      // ASSERT
      assertThatThrownBy(() -> future.join())
          .isInstanceOf(CompletionException.class)
          .hasCauseInstanceOf(StorageException.class)
          .hasMessageContaining("S3 unavailable");
    }

    @Test
    @DisplayName("Should propagate LogContext to async operation")
    void givenLogContext_whenUpload_thenContextPropagated() throws Exception {
      // ARRANGE
      AtomicReference capturedContext = new AtomicReference<>();

      doAnswer(invocation -> {
        capturedContext.set(CustomLog.getCurrentContext());
        ((Runnable) invocation.getArgument(0)).run();
        return null;
      }).when(executorService).execute(any(Runnable.class));

      // ACT
      fileStorageService.uploadOriginalFile(testInputStream, 1024L,
          testLogContext, InvoiceFormat.UBL).join();

      // ASSERT
      assertThat(capturedContext.get

…

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [affaan-m](https://github.com/affaan-m)
- **Source:** [affaan-m/ECC](https://github.com/affaan-m/ECC)
- **License:** MIT
- **Homepage:** https://ecc.tools

Install and usage instructions live in the source repository linked above.